"The test really begins now for Harry and Meghan," he declared, per Closer. "They have come to the U.K. and to the Jubilee and really cemented themselves as royals again – which is great for their brand and something that Spotify, Netflix and [book publisher] Penguin will be eating up. But everything now depends on their behavior moving forward."
Duncan reportedly believes that behind closed palace doors, there was likely some "tension, awkwardness and wariness" between the couple and the royals, and if the former actress, 40, or dad-of-two, 37, disclosed those details in his upcoming memoir or in another televised interview, their chance of ever mending ties will be over for good.
"It’s last-chance saloon for them now. If anything from the weekend leaked, I imagine they will be totally cut off and that’ll be it. It’s very dangerous ground if they betray anyone now," explained the author. "But if they act appropriately and prove they can be trusted, it could be a huge step in the right direction and the start of a new beginning."
The writer reportedly thinks it's "great" that the Sussexes came to the event, as it seemed to serve as an "olive branch" from the royals, but their presence also "cast a bit of a shadow over the whole thing for the royals."
Indeed, one of the biggest headlines from the festivities centered on the obvious discord between Harry and the Cambridges, as Prince William, 39, and Kate Middleton, 40, sat on the opposite side of the church from him and Meghan during the Service of Thanksgiving.
Additionally, neither the parents-of-three nor their kids were present for Lilibet's first birthday because they had a previous commitment — though royal expert Christopher Anderson claimed that overall, "William and Kate made no effort at all to introduce Prince George, Princess Charlotte and Prince Louis to [Lili]. As far as I know, nobody believes they spoke [to one another]."